1. Field of the Invention
The present invention relates to a thin-film magnetic writing head used as, for example, a floating magnetic head. More particularly the present invention relates to a thin-film magnetic head which is provided with a thick coil to reduce the electrical resistance. Furthermore, the present invention relates to a method for manufacturing the magnetic head.
2. Description of the Related Art
Inductive writing heads of which coil layers are formed on lower core layers composed of magnetic materials are disclosed in Japanese Unexamined Patent Application Publication Nos. 2001-076320 and 2002-025009.
Recently, the recording density of such writing heads has been improved and the size of magnetic heads has been reduced. As a result, a reduction in size of a pole portion has been in demand.
To address the high recording density, a planar inductive magnetic head having a planarized upper core on a lower core is disclosed in U.S. Pat. No. 6,353,511.
The magnetic head disclosed in U.S. Pat. No. 6,353,511 exhibits an improved recording density compared with those disclosed in Japanese Unexamined Patent Application Publication Nos. 2001-076320 and 2002-025009. In such a magnetic head having a high recording density, the coil must be disposed in a very narrow space because of the reduced size of the magnetic head. Therefore, the coil itself must be small. In such a structure, the cross-sectional area of the coil becomes narrow and the resistance of the coil is increased.
When the resistance of the coil is increased, a recording current flowing in the coil generates a large amount of Joule heat and the temperature in the inductive head rises significantly.
The thermal expansion coefficient of a metal material which forms the coil or the core is different from that of an insulating material which covers the coil or the core. Therefore, when the temperature in the inductive head rises, the inductive head portion may protrude from an opposing face because of the difference in thermal expansion coefficients, that is to say, pole tip protrusion (PTP) occurs.
When the PTP occurs, the frequency of collision of the inductive head with the recording medium increases. As a result, the recording medium and the inductive head are easily damaged.